Tension-holding member for concrete-reenforcement-tensioning devices



H. SORENSEN Dec. 16, 1930.

TENSION HOLDING MEMBER FOR CONCRETE REENFORCEMENT TENSIONING DEVICES Filed Oct. 5, 1927 IN VE N TOR wrg.

Patented Dec. 16, 1930 HENRY SORENSEN, or sen rnnncrsco, CALIFORNIA TENSION-HOLDIN G MEMBER FOR CONGRETE REENFRGEMENT-TENSIONING DEVICES I Application filed October 3, 1927. Serial No. 223,722.

I have described my invention in the following specification and the accompanying drawings. I, 1

Although my invention adapts itselffor use in connection with any known tensioning device, I have, nevertheless, in addition to the description of my invention, also described a specific form oiftensioning device, in connection with which my invention may be used. l I

While my. invention may be applied in various ways, I have described it applied to,

the floors of fireproof buildings.

, In the 'drawings:' i I Fig. 1 is a side viewof-my invention, prior to the tensioning of the reenforcement.

Fig. 2is an end view of Fig.1 at A,A.

Fig. 3is a face view of Fig. 1 -at.A.-A.

Fig. 4. is a side view of Fig. l at AA', after the tensioning is done. g Fig. 5 is a side view of the finishedfloor, but before the temporary strut member and the forms are removed.

' Similar parts of the drawings are indicated by similar numerals.

Numeral 1 designates the reenforcement. 2 is a hooked end of reenforcement 1. 3 is the opposite end, to hook 2, ofre'enforcement 1. 4 designates beams which are supported by' columns, not shown. .5; designates a stretching bar. 56 designates a bracing ridge on stretchingbar 5. 6 is a split end of stretching'bar 5. 7 designates sharp edges of the split end 6'. 8 is the handle of the stretching bar. 9 is a safety catch for bar 5. 10 is the safety catch pin. 11 is the hook of safety catch 9. 12 designates a strut. 13 are wedges. 14 are the strut supports. 15 are the concrete forms. 16 areboxed openings in the concrete forms 15. 17 designates the concrete.

I. attach the one end of reenforcement'l to the flange of the one, ofthe two opposed beams 4, by means of book 2, andI let the opposite end 3, of reenforcement 1, rest upon,

and extend beyond,the flange of the other beam 4.

I thereupon drive the sharp edges 7, of the splitend 6, of bar 5, firmly across reenforcement 1, atthe point Where end 3, of reenforcement 1, extends over the flange of beam 4. The edges 7, of the split end 6, are

abrupt and sharp,such as is the case with heavy steel cutting tools, and are made of harder material than reenforcementl 1, so that the said edges 7 readily bite into, and grip, reenforcement 1, when bar 5 is driven, as above described. This is done to provide edges 7 with the necessary strength to stand the strains to whichsaid edges are subjected. Stretching bar 5 is adapted to fit reenforcements. of various diameters, due to the increasing Width of split end 6.

' In order to tension reenforcement 1 t0 beams 4, handle 8, of stretching bar 5, is pushedin the direction ofthe arrow, as shown on Fig. 4, after split end 6 is driven into reenforcement 1, as above described. When handle 8 is pushed forward that part of split end, 6,,which points downwards below reenforcement 1, will press against the edge ofqthe flange'of beam 4, whereby the edges 7 Willv force end 3 forward, and thereby stretch, or tension reenforcement 1. Due'to the, short distance, between the point, where split 6 grips end 3, and the point. where split 6 presses against the flange of beam 4, the

length of bar 5 will exercise a great tensioning power upon reenforcement 1, when handle 8 is pushed forward. 1

The operator holds handle 8, in its tension- 7 ing position, with one hand, while, with the other hand, he'drives end 3 round the flange of beam 4 by means of a hammer. On Fig. 4 I have shown the position of bar 5, when reenforcement l. is tensioned. Bar 5 is then at an angle relative to its original position, as shown in Fig. 1.

When reenforcement 1 is tensioned, as above described, end 3 becomes slightly inclined, downwards, which is caused by the tilting of bar 5, as it draws end 3 over the flange of beam 4. The split end 6 is wedgeshaped, with its point tapering downwards, End 3 will, therefore, immediately be released from the grip which split 6 has upon it, when end 3 is struck downwards, as above described. Due to the downward kink, which end 3 has received, over the flange of beam 4, an experienced operator will readily bend 3 downwards, with one blow of the hammer, past the point where end 3 might swing back over the flange of beam 4.

IVhen the operator strikes the blow which, as above described, releases end 3 from the grip which bar 5 has upon it, bar 5 would drop, were it not for safety catch 9, which is attached to the bracing ridge 5?), of bar 5, by means of pin 10. Hook 11, of safety catch 9, is bent well in so that it may grip the inside part of the flange of beam 4. When bar 5 is in its normal, vertical, position, there is a suitable play between hook 11 and the flange of beam 4, as shown on Fig. 1, but when bar 5 is in the position of having fully tensioned reenforcement 1, hook 11 has engaged the flange of beam 4, as shown on Fig. 4. WVhen the operator drives end 3 downwards, as above described, hook 11 will immediately function and prevent bar 5 from dropping, and hold bar 5 in place, so that the jerk, caused by the sudden release of end 3, will not throw the operator, who is pushing against handle 8 with one hand, out of his balance.

After having dealt with the above I am now coming to that which constitutes my invention, herein.

I strut the beams 4 against the inward draw, which is caused by the initial tension ing of reenforcement 1, and while the strut may be constructed in various ways, I prefer to strut the beams 4 in the following manner:

As shown on Fig. 1 and on Fig. 5, I divide strut 12, which I prefer to make of wood, in two parts, for the reasons which I will explain later, and I tighten the two parts of strut 12, snugly against beams 4, by means of wedges 13, which I place between the two parts of strut 12. I support strut 12 by means of posts 14.

By placing strut 12 the right distance be low reenforcement 1, strut 12 will serve the purpose of a support for floor form 15, besides serving as a strut between beams 4.

lVhile any known suitable infilling material may be used, I have, In Fig. 5, shown the infilling as concrete 17 which is poured upon the forms 15; and I have also shown end 3, embedded in concrete 17 bent round, and locked to beam 4, after reenforcement 1 is tensioned to beams 4, as hereinbefore described.

Strut 12 is not removed before concrete 17 is hard. The stiffness of the concrete floor,

itself, will then act as a strut between beams 4. "When forms 15 are placed around beams 4, I place boxes 16 around the two ends of strut 12. When strut 12 is to be removed I first extract wedges 13, which enables me to remove strut 12 in two parts, by first parting the middle ends sideways and then extracting the one part past the other. After boxes 16 are removed the holes, which were left in concrete 17 by boxes 16, are filled.

Had I not availed myself of the use of strut 12, which is placed between, and contacts, the beams 4, then the draw,-which is caused by the stretched position of the tensioned reenforcement 1,would have caused the beams 4 to deflect inwardly, due to the fact that reenforcement 1 is locked to the beams 4. This inward deflection of the beams 4 would then, in turn, allow reenforcement 1 to shrink, and the tension, which was initially injected into reenforcement 1, would thereby be lost. Strut 12, however, holds beams 4 in place, by resisting their deflection, and in that way strut 12 operates (through beams 4) upon reenforcement 1, to hold its tension, until concrete 17 has set into cohesion with reenforcement 1. I have described how strut 12 is removed, after the concrete 17 has set into cohesion with reenforcement 1, and the said cohesion,which acts along the whole length of reenforcement 1,-will thereupon, permanently hold the tension, in reenforcement 1, because the hardened concrete 17 then takes the place of the removed strut 12 and prevents reenforcement 1 from shrinking from its tensioned position. The reaction of the tension (in the stretched reenforcement 1) clamps the concrete 17 together. No pressure from the outside can act upon concrete 17, before that outside pressure has first absorbed the said initial tension, which was given to reenforcement 1.

Various modifications of construction may be made without departing from the spirit of my invention.

I claim:

' 1. In a device to impart initial tension into the reenforcement of an infilled structure including means'to hold said reenforcement to a support of the structure while under tension, the combination of a member adapted to strut said support against said tension, said member being isolated from the infilling, whereby said member may be removed after said infilling has set into cohesion with said reenforcement.

2. In a device to impart initial tension into the reenforcement of an infilled structure including means to hold said reenforcement to a support of the structure while under tension, the combination of a member adapted to strut said support against said tension, and a casing isolating said member from the infilling, whereby said member may be removed after HENRY SORENSEN. 

